File Verifier++ is a useful Windows application that can help you confirm that a set of files haven't been changed. Which may sound a little odd, but actually it has several worthwhile applications.

Do you regularly back up files to CD or DVD, for instance? These may become corrupt over time, but usually there's no way to tell this. File Verifier++ can generate digital fingerprints called hashes for each file, though, and then save these on the discs as well. They may then be used at any time to verify that the backups are still good.

Or maybe you're concerned about malware? Create hashes for your Windows or Program Files folders, say, and that will help you spot any files that have been modified later.

And you might similarly use the program as an advanced troubleshooting aid. If you keep suffering PC problems every time you install a particular program, for instance, then hashes will let you know which system files it might have changed.

An Explorer shell extension makes the program easy to use, as you can generate hashes from the right-click menu for files and folders.

But there's also plenty of power available for experts, including support for more than 20 hashing algorithms, a command line version of the tool, and powerful search options that allow regular expressions.

Verdict:

File Verifier++ makes it easy to verify the integrity of your backups, and it has several other interesting applications. A worthwhile addition to your technical toolbox

Spotlight: Free Full Software

WhatsApp Messenger is the world's most popular instant messaging app for smartphones.

You can use it to send and receive text and voice messages, photos, videos, even call your friends in other countries, and because it uses your phone's internet connection it might not cost you anything at all (depending on whether you'll pay data charges).

It's easy to set up and use. There's no need to create and remember new account names or pins because it works with your phone number, and uses your regular address book to find and connect you with friends who use WhatsApp already.

You can talk one-to-one or in group chats, and because you're always logged in there's no way to miss messages. Even if your phone is turned off, WhatsApp will save your messages and display them as soon as you're back online.

There's plenty more (location sharing, contact exchange, message broadcasting) and the app is free for a year, currently $0.99/ year afterwards.